The present invention relates to a method and apparatus for processing thermally developable film and electronically extracting scene information from that film. It particularly relates to a compact apparatus and method for developing film by applying heat to the film.
In the conventional practice of color photography, silver halide film is developed by a chemical technique, requiring several steps consisting of latent image development, bleaching, and fixing. While this technique has been developed over many years and results in exceptional images, the technique requires several liquid chemical solutions and precise control of times and temperatures of development. Further, the conventional silver halide chemical development technique is not particularly suitable for utilization with compact developing apparatus. The chemical technique also is not easily performed in stand alone units as might be appropriate for self-operated kiosks, the home or the small office.
The method of electronic film development has been proposed as an alternative to conventional wet process methods. In this method, a conventional color film is developed by applying a viscous black-and-white developer solution under a laminate. Density formation during and following development is monitored by a sequence of both infrared transmission and reflection scans. The reflection scan of the front surface of a film is said to represent a blue color record, while the reflection scan of the rear surface of a film is said to represent a red color record. The transmission scan is said to represent the sum of the red, green and blue color records. The green color record is then said to be extractable by difference. This method, as described in Edgar U.S. Pat. Nos. 5,465,155; 5,519,510; and 5,790,277, is inadequate in that development is inherently uneven and leads to uncorrectable defects in the formed images. It has recently been proposed by Edgar U.S. Pat. No. 5,988,896 that the method can be improved by the expedient of applying developer solution by means of micro-droplets instead of by viscous solution and lamination. However, development remains functionally uncontrolled. In the improved method, only limited quantities of developer solution are applied because application of excess developer solution in the form of micro-droplets still leads to non-uniformity of development and run-off. The required quantity of developer solution required in each area of film is ultimately determined by the exposure in that area. Since the exposure cannot be determined until after development, high exposure areas are under supplied with developer or low exposure areas are oversupplied with developer with the result that highly exposed regions are underdeveloped while low exposure areas are overdeveloped with variation in density formation corresponding to the pattern of droplet application. The effect can be especially apparent under conditions of high magnification as is required for the production of prints from films designed to be employed in hand held cameras.
Imaging systems that do not rely on conventional wet processing have received increased attention in recent years. Photothermographic imaging systems have been employed for producing silver images. Typically, these imaging systems have exhibited very low levels of light sensitivity and have been utilized primarily where only low imaging speeds are required. The most common use of photothermographic elements is for copying documents and radiographic images. A method and apparatus for heat developing microfilms is disclosed in Lewis U.S. Pat. No. 4,194,826, while a method and apparatus for heat developing sheet films is disclosed in Islam et al U.S. Pat. No. 5,587,767. Summaries of photothermographic imaging systems are published in Research Disclosure, Vol. 170, June 1978, Item 17029, and Vol. 299, March 1989, Item 29963. Thermally developed films have not been generally utilized in camera speed color photography due to the difficulties of forming optically printable color images from heat development color photographic materials. Several approaches have been proposed, for example, by Cerquone et al U.S. Pat. No. 4,021,240; by Taguchi et al U.S. Pat. No. 5,698,365; by Ishikawa et al U.S. Pat. Nos. 5,756,269 and 5,858,269, and in U.K. Publication 2,318,645. These all rely either on partial wetting and lamination and image transfer schemes or on optical color printing or scanning through both developed silver and formed dye. The image transfer schemes are suitable for directly producing prints. However, they are not suitable for images that need to be magnified, as for example images captured on roll films sized to be loaded into cameras, since these images lose resolution or detail in being transferred from a donor to a receiver sheet. This resolution loss is visually objectionable. Examples of low sensitivity, low-resolution commercial products include Color Dry Silver supplied from Minnesota Mining and Manufacturing Co. and PICTROGRAPHY(copyright) and PICTROSTAT(copyright) supplied by Fuji Photo Film Co., Ltd. Optical color printing and color scanning both require transmitting light through an image. The transmitted light may be used to directly expose another film or its intensity may be measured electronically and the electronic record of the transmitted light may be digitized and stored as an electronic file representation of the film image. These techniques are not readily applied to photothermographic films because of the high formed densities and because the color records are all contaminated by undeveloped silver and by imagewise black silver density deposits that cannot be unambiguously associated with distinct color records.
There is a need for a compact, camera speed color film development and reading system that can be utilized in stand-alone units as might be appropriate for self-operated kiosks, the home or the small office. There is a further need for a compact thermal development film development and reading system with the capability to scan the thermally developable film having both silver density and independent color records.
It is an object of the invention to overcome disadvantages of prior apparatus and processes for thermal film and the complicated, awkward procedures for wet-processing conventional films.
It is another object to provide an improved method of development of thermal film in a thrust cartridge.
It is another object to provide more convenient and rapid processing of thermal film to the individual user.
It is another object to provide a means to scan the thermal film.
It is yet a further object to provide simplified films suitable for scanning.
It is yet another object of this invention to provide a method of scanning simplified films.
These and other objects of the invention are accomplished by an apparatus for thermal development having a receiver for receiving an imagewise exposed thermal film, an accumulator for gathering the film, a drive for advancing the film from the receiver to the accumulator, a heater located between the receiver and the accumulator for developing the film as it passes between the receiver and the accumulator, an image scanner for scanning the film after it has been thermally developed, the scanner having a first light source and a first sensor placed for forming a first electronic record of the image formed on the developed thermal film by reflection, a second light source and a second sensor placed for forming a second electronic record of the image formed on the developed thermal film by an opposing reflection, and a third sensor and a third light source placed for forming a third electronic record of the image formed on the developed thermal film by transmission, wherein the third sensor may be the same or different than the first sensor and the third light source may be the same or different than the second light source; and a lighttight container for the receiver and the heater.
The objects of the invention are additionally provided by an image forming method comprising the step of scanning an imagewise exposed and thermally developed silver halide film element to form a first electronic record of the image formed on the developed thermal film by reflection, a second electronic record of the image formed on the developed thermal film by an opposing reflection and a third electronic record of the image formed on the developed thermal film by transmission.
The objects of the invention are further provided by a light sensitive silver halide color thermal film element comprising red, green and blue light sensitive layer units wherein the layer units form reflective images of substantially similar color on thermal development or wherein the element is substantially free of color forming components.
The invention provides a compact, convenient apparatus and method for processing of film, especially camera speed film contained in a thrust cartridge. It provides a means to scan the thermal film to form an electronic record of image data that may be readily processed, printed, and transmitted. It provides a means to record and write magnetic information to effect optimal subsequent processing. It provides an apparatus and a method of processing of color thermal films that is convenient, compact and overcomes the need for wet chemicals, water and sewer hookups and constant operator attention while overcoming the shortfalls inherent in previous thermal films and processes.